Fixes #32192 - Handle special characters in HTTP proxy credentials

Originally we tried to using user provided credentials verbatim, leading to
errors when they contained special characters. This is resolved by escaping them
first.

app/models/http_proxy.rb

@@ -1,3 +1,5 @@
+require 'cgi'
+
 class HttpProxy < ApplicationRecord
   audited
   include Authorizable
@@ -31,8 +33,10 @@ class HttpProxy < ApplicationRecord
 
   def full_url
     uri = URI(url)
-    uri.user = username if username.present?
-    uri.password = password if username.present?
+    if username.present?
+      uri.user = CGI.escape(username)
+      uri.password = CGI.escape(password)
+    end
     uri.to_s
   end